Preparation of crosslinked β‐cyclodextrin polymer beads and their application as a sorbent for removal of phenol from wastewater

BACKGROUND: Phenols are commonly encountered in aqueous effluents from various manufacturing processes such as oil refineries, coke plants, and phenolic resin plants, and are toxic substances that should be removed from the aquatic environment. This paper reports on the preparation of beaded crosslinked β‐CyD polymers, and the removal of phenol by the β‐CyD adsorbent from raw industrial wastewater discarded from phenolic resin processing. RESULTS: Crosslinked β‐CyD prepolymer was synthesized by treatment of β‐CyD with hexamethylene diisocyanate (HDI) at a molar ratio of 1:8. The suspension of the resulting powdery prepolymer in aqueous sodium alginate was added dropwise into an aqueous calcium chloride solution to precipitate the spherical β‐CyD prepolymer gels. The spherical prepolymer gel was lyophilized and re‐crosslinked with HDI to provide the β‐CyD polymer beads. The physical properties of the beads were as follows: average diameter: 3.4 mm; average compressive strength: 2.17 MPa; porosity: 47.0%; specific surface area: 3.48 m² g^?1. The removal of phenol from raw industrial phenolic wastewater with the β‐CyD polymer beads was carried out in either a shaker or an upflow column at 25 °C. After seven episodes of accumulated adsorption, the initial phenol concentration of 89000 ppm decreased to as low as 350 ppm in the shaker and 490 ppm in the upflow column. CONCLUSION: Adsorbent [β‐CyD/HDI(1/8)]/HDI polymer beads having a good regular shape and high mechanical stability were newly prepared by a stepwise crosslinking method. The results of sorption experiments show that the beads exhibit high sorption capacities for phenolics in raw industrial wastewater. Copyright © 2008 Society of Chemical Industry     

A cost‐effective crosslinked β‐cyclodextrin polymer for the rapid and efficient removal of micropollutants from wastewater

Water pollution problems pose a serious threat to the health of humans and other living organisms due to the increasing global contamination of various water resources by organic micropollutants, such as plastic components, dyes and pesticide intermediates. It has been a challenging problem to remove these organic micropollutants, despite various attempts. Here, we report a novel, cost‐effective and water‐insoluble crosslinked β‐cyclodextrin polymer for the efficient removal of various organic micropollutants from wastewaters with excellent adsorption capacity, large removal rate, robust performance and reusability. This polymer can remove 93% of bisphenol A within 1 min with an equilibrium uptake of 38 mg g^?1 and a maximum adsorption capacity at equilibrium of 139 mg g^?1. This is the fastest removal performance that has been reported so far, showing a bright future towards practical applications. © 2019 Society of Chemical Industry     

Efficient recovery of phenol from phenolic wastewater by emulsion liquid membrane

The recovery of phenol from phenolic wastewater by emulsion liquid membrane (ELM) was investigated. The W/O emulsion was prepared with kerosene, Span−80, carrier, liquid paraffin, and NaOH solution. The effects of NaOH concentration, oil–internal solution ratio, shearing speed, Span−80 concentration, and carrier type and concentration on emulsion breakage were studied. In the single factor experiments of stability of W/O emulsion, the lowest percentages of emulsion breakage were achieved at a NaOH concentration of 0.03 g/ml, an oil–internal solution ratio of 2:1, a shearing speed of 1500 r/min, a Span−80 concentration of 8%, a tributyl phosphate (TBP) concentration of 0.8%, and an ethyl acetate concentration of 0.8%, respectively. Then, the effects of nine factors on extraction efficiencies of phenol were investigated. This indicated that the effects of shearing speed, oil-internal solution ratio, emulsion-external solution ratio, liquid paraffin concentration, and mixing speed on extraction efficiencies of phenol were limited. However, the carrier concentration, NaOH concentration, Span−80 concentration, and phenol concentration had important impacts on the extraction efficiency of phenol. The extraction efficiency of phenol could reach 99.7%. Besides, the results of orthogonal experiments indicated that during the extraction of phenol by ELM, the order of importance of factors was NaOH concentration > emulsion-external solution ratio > volume fraction of Span−80 > volume fraction of TBP. After extraction, the recycled emulsion with Span−80 could not easily be effectively demulsified through heating, which only provided the highest demulsification efficiency of 18.2%. However, the recycled emulsion could be effectively demulsified through centrifugation, which could get the highest demulsification efficiency of 86% at a centrifugal rotational speed of 2000 r/min and a centrifugal time of 25 min.     

聚环糊精填充PDMS渗透蒸发膜分离苯酚水溶液

以聚二甲基硅烷为预聚体,正硅酸乙酯为交联剂,二丁基二月桂酸锡为催化剂,三氯甲烷或正庚烷为溶剂,通过相转化法制备得到了空白聚二甲基硅氧烷（PDMS）膜和聚环糊精（CDP）填充PDMS（CDP-f-PDMS）膜.考察了空白PDMS膜和CDP-f-PDMS膜对苯酚水溶液的渗透蒸发分离性能,证明填充膜优于空白膜.还分别考察了溶剂类型、填充剂用量等制膜因素和操作温度、原料液流量、原料液浓度等操作因素对PDMS膜的渗透蒸发分离性能的影响.当温度为60℃,CDP填充量为1%（质量）时,CDP-f-PDMS膜的渗透通量和分离因子分别可达32.0 g•m-²•h^-1和7.2.     

超声作用联合纳米腐植酸处理苯酚废水

采用静态吸附法研究了超声联合纳米腐植酸处理苯酚废水;用红外光谱(FT-IR)、扫描电镜(SEM)、比表面积测试仪(BET)对纳米腐植酸的粒径大小、形貌、比表面积及孔径等进行表征,结果表明:纳米腐植酸粒度分布均匀,平均粒径为50 nm,比表面积为110.31 m2/g,孔径为6.56 nm;考察了苯酚初始浓度、纳米腐植酸用量、超声声强及频率等因素对纳米腐植酸和超声作用协同处理苯酚废水的最佳工艺条件。实验结果表明:超声频率为20 kHz,超声声强0.2 W/cm2,苯酚初始质量浓度为100 mg/L,pH值为6.0,溶液体积100 mL,吸附温度40℃,吸附时间120min,纳米腐植酸用量为40 g/L的条件下,纳米腐植酸与超声作用协同处理苯酚废水吸附率可以达到95.7%;吸附剂纳米腐植酸对苯酚的吸附主要受颗粒内扩散所控,其再生循环使用5次后,苯酚的吸附容量仅减少18.9%。     

Heavy metal ions removal from wastewater using electrocoagulation processes: A comprehensive review

A vast number of publications have investigated the application of electrocoagulation (EC) process in heavy metal ions removal from wastewaters. Most of these studies were simple lab-scale using synthetic wastewater with the absence of holistic and systematic approach to consider the process complexity. This comprehensive review considers the fundamental aspects of EC processes such as mechanisms, kinetic models, and isotherm models used by different researchers. Furthermore, the impact of the main design and process operational parameters on the removal efficiency is discussed and analyzed. Many concluding remarks and perspectives are stated to give insights for possible future investigations.     

煤化工废水萃取脱酚流程模拟

为提高煤化工高浓度含酚废水萃取脱酚的处理效果,减轻废水排放环境污染,采用Aspen Plus流程模拟软件对煤化工废水萃取脱酚流程进行了优化设计。模拟采用真实煤化工废水的组成设置物流数据,废水进料流量为100 t/h,温度为40℃,压力为0.1 MPa,并利用UNIQUAC和NRTL活度系数模型,分别对萃取脱酚塔、溶剂回收塔、溶剂汽提塔进行了参数调整。模拟结果表明,当萃取脱酚塔萃取级数n=6,萃取相比R=1∶4时;溶剂回收塔的理论塔板数N=10,进料位置为第5块塔板时;溶剂汽提塔的理论塔板数N=5,进料位置为第1块塔板时,废水总酚浓度从18 600 mg/L降至400mg/L以下,单元酚浓度从14 000 mg/L降低至50 mg/L以下,萃取剂回收利用率达到99%以上。     

Study of phenol removal using fluidized-bed Fenton process

In this paper, the removal of phenol from simulated wastewater was studied using gas–liquid fluidized bed with the Fenton reagent. The factors that affect the removal rate of phenol were investigated, including the initial concentrations of hydrogen peroxide [H₂O₂] and [Fe²⁺], the molar ratio of [Fe²⁺]/[H₂O₂], pH value, temperatures, reaction time, and the ventilation volume. It was found that the optimal operating conditions existed as: [H₂O₂] = 12 mmol/L, [H₂O₂]/[Fe²⁺] = 4:1, pH = 4, T = 60 °C, reaction time of 30 min, and a ventilation volume of 0.12 m³/h. Under these conditions, the phenol removal rate of about 96% was obtained.     

煤气化高浓酚氨废水处理技术研究进展

煤化工废水中以鲁奇炉和BGL炉为代表的固定床气化洗气废水氨氮和酸性气含量高,且含有高浓度生物毒性的酚类物质,COD高达20000~50000mg/L,形成煤化工废水处理的技术瓶颈问题。本文首先对国内外不同技术进行分析对比,阐述各酚氨处理技术优缺点和工业实施状况。分析表明脱酸脱氨再萃取脱酚技术效果较好,该工艺采用单塔脱酸侧线脱氨将废水pH调至中性利于萃取脱酚,采用新型萃取剂,提高多元酚的分配系数,总酚萃取回收率可达93%。文中详细介绍该工艺中关键装置主要技术参数,如塔的操作温度和压力、精馏塔内回流比、进料位置、萃取塔内相比、萃取级数等。最后介绍了该工艺在哈尔滨煤化工公司煤气化项目的废水处理实例,废水处理量为5000t/d。新流程的处理效果和运行成本具有明显优势。该工艺目前又在中煤能源集团有限公司鄂尔多斯能源化工公司图克化肥项目的煤气化废水处理中获得成功应用。     

脉冲电源电解处理含氰含银电镀废水

利用脉冲电源从含氰含银电镀废水中回收银和去除氰,对比了脉冲电源与直流电源对含氰镀银废水的处理效果,系统研究了脉冲电源的电解电压、占空比和脉冲频率等参数对电能消耗、银回收率和除氰率的影响。结果表明,脉冲电源较直流电源能更加有效降低阳极的超电位,减少电极的极化,从而降低槽电压,进而有效地降低电能消耗。脉冲电源的优化参数是：脉冲电压2.0 V,脉冲频率1200 Hz,占空比50%。在循环流速100 ml·min^-1,pH值10～11,曝气速率1.0 L·min^-1的实验条件下,通入电解电压2.0 V、脉冲频率1200 Hz以及占空比50%的脉冲电源,电解2.0 h后,银回收率高达99%,除氰率达到86%。     

Dye removal from colored textile wastewater using acrylic grafted nanomembrane

In this paper, the dye removal ability of the acrylic grafted polysulfone nanomembrane using ultraviolet radiation was studied to remove dyes from colored textile wastewater. Acrylic acid was used to modify polysulfone ultrafiltration membrane. The effect of different operating parameters such as pressure, salt concentration and chemical structure of dyes was evaluated. Data indicated that the photografted membrane has acceptable performance both in terms of flux and rejection. The dye rejection and hydraulic permeability were 86–99.9% and 7.6 L m^{− 2} h^{− 1} bar^{− 1}, respectively. It was found that the rejection of dyes decreased with salt concentration due to a decrease of the Donnan effect. Also, the low molecular weight dyes and highly charged dyes were more sensitive in the presence of salts. Addition of 80 mM Na₂SO₄ in dye solution decreased the dye rejection more than 15%. The rejection enhancement for all cases was negligible by increasing driving pressure from 1 to 4 bar. Dyes with low charger were more sensitive to operating pressure than that of dyes with higher charges. All findings supported that acrylic grafted nanomembrane is potentially capable to separate dyes from colored textile effluent.     

COD removal from actual industrial wastewater using a three-dimensional electrochemical apparatus

Chemical oxygen demand (COD) removal was investigated using a three-dimensional electrochemical system. The effects of electrode position, pH value, initial temperature, circulation flow, aeration, and addition of hydrogen peroxide on the removal efficiency of the pollutant were studied. The fillers used in the experiment were centimetre-sized and electrolyte was obtained from an industrial factory with a concentration of COD as high as 25 000–27 500 mg L⁻¹, which was rare in other studies of the past. The degradation of organics was affected by pH and circulation flow, and a decrease in the initial pH value led to the increase in removal efficiency, while a trend of increasing at first and then decreasing was observed with the extension of circulation flow. Aeration and hydrogen peroxide served as enhanced processes for a higher removal rate. Both ultrasound and ultraviolet had effects on the electrolysis system. Oxygen uptake rate measurement and bio-treatment experiments demonstrated a significant increase in biodegradability with this three-dimensional electrochemical system. In addition, a pilot scale test in a pharmaceutical factory showed an economic benefit on energy consumption, which was as low as 10 kWh  kg⁻¹ COD.     

Dye removal from colored textile wastewater using chitosan in binary systems

In this paper, the removal of two anionic dyes from textile effluent in single and binary systems was investigated. Direct Red 23 and Acid Green 25 were used as anionic dyes. The surface characteristics of chitosan were investigated using Fourier transform infrared. The effects of operational parameters such as chitosan dosage, initial dye concentration, salt and pH on dye removal were studied. The isotherms of dye adsorption were investigated. It was found that the isotherm data of Direct Red 23 and Acid Green 25 in single and binary systems followed Tempkin isotherm. In addition adsorption kinetics of dyes was studied in single and binary systems and rate sorption was found to conform to pseudo-second order kinetics with a good correlation. Results indicated that chitosan could be used as a biosorbent to remove the anionic dyes from contaminated watercourses in both single and binary systems of pollutants.     

Utilization of bagasse fly ash generated in the sugar industry for the removal and recovery of phenol and p-nitrophenol from wastewater

Bagasse fly ash, a waste generated in local sugar industries, has been converted into a low cost adsorbent. The product so obtained has been characterized and used for the removal of phenol and p-nitrophenol. Investigations include the effect of pH, sorbent dosage, phenol concentration and the effect of surfactants on the uptake of phenol and p-nitrophenol. The adsorption data follow both Langmuir and Freundlich models. Isotherms have also been used to obtain the thermodynamic parameters of the process. Some experiments have also been performed with a view to recover phenols and have in-situ chemical regeneration of the spent carbon column. © 1998 SCI.     

生物质煤气废水氨氮脱除的研究

生物质煤气废水是一种新出现的高浓度氨氮有机废水.作者采用化学沉淀法去除该废水中的氨氮,研究了不同沉淀剂、pH、温度和搅拌时间对氨氮去除效果的影响.结果表明,MgCl2 Na3PO4·12H2O明显优于其他沉淀剂组合.当n(Mg2 )∶n(NH4 )∶n(PO3-4)=1∶1∶1、pH 10.0、温度30 ℃、搅拌时间30 min时,废水中的氨氮质量浓度从处理前的222 mg/L降到17 mg/L,去除率为92.3%.     

Contaminants and salinity removal of olive mill wastewater using zeolite nanoparticles

Successive columns of gravel, fine sand, and mixture of acidified cotton and zeolite clinoptilolite nanoparticles (ZNP) were found efficient in olive mill waste water (OMW) treatment and desalination. The treatment decreased OMW’s salinity from 10.9 to 1.6 dSm^?1 due to K⁺ removal. Furthermore, most total phenol contents were removed. The adsorption of K⁺ (aqueous solution) onto normal zeolite particles (NSP) and ZNP indicated that the pseudo-second order kinetic model is best model for K⁺ adsorption. Langmuir model was best fit model for K⁺ adsorption equilibrium. K⁺ maximum adsorption capacities were 7.2 and 16.5 mgg^?1 for NSP and ZNP, respectively.     

高浓度酚醛树脂生产废水处理工程实例

针对某磨料磨具厂酚醛树脂生产废水的高酚醛水质特点,采用Fenton—混凝沉淀—生物接触氧化工艺对废水进行处理。实际运行结果表明,在进水平均COD≤10 000 mg/L,甲醛≤1 200 mg/L时,出水COD≤110 mg/L,甲醛≤0.1 mg/L,出水水质达到《水污染物排放限值》(DB 44/26—2001)二级排放标准。工程实践证明,该工艺处理效果良好、出水水质稳定。     

Phosphorous removal from wastewater by lanthanum modified Y zeolites

The adsorption capacities of Y zeolite and La (III)-modified Y zeolite were studied. A series of La(III)-modified Y zeolites with different La/Y zeolite mass ratios were characterized by X-ray diffraction, X-ray fluorescence and Brunauer-Emmett-Teller surface area analysis. Batch experiments were conducted to evaluate the effects of various experimental parameters, such as pH, ionic strength, coexisting anions (CO32-, Cl^-, SO42- and NO3-) and temperature, on the phosphate adsorption. The capacity of the La (III)-modified Y zeolite to remove phosphate increased as the La/Y zeolite mass ratio increased and after 4 h, a phosphate removal efficiency of 95% was achieved for a La/Y zeolite mass ratio of 0.10. The equilibrium adsorption isotherm data correlated better to the Langmuir model than the Freundlich model and the data followed a pseudo-second-order kinetic equation.     

Study on adsorption characteristic of macroporous resin to phenol in wastewater

The removal of phenol from solution was investigated using macroporous resin. The effects of initial concentration, pH, and temperature on phenol removal were studied. The experimental results indicated that the adsorption capacity reached equilibrium state within 20 min and adsorption followed pseudo‐second‐order kinetic model. Langmuir isotherm model could be better to describe the isothermal adsorption of phenol, the maximum adsorption capacity (Q_m) and Langmuir constant (K_L) were 103.64 mg/g and 0.2719. Macroporous resin after reached to saturation has a high desorption percentage, indicating that H‐103 is an excellent reusing adsorption material. It provided theoretical references for practical application in phenolic wastewater treatment.